The present invention relates to an intraluminal device, suitable for implantation in a body, which intraluminal device is provided with a coating.
Intraluminal devices of the above mentioned type are generally known and applied. Such devices are for example applied in the treatment of blood vessel blockage in which the blocked blood vessel first is dilated, followed by placing a vascular prosthesis, in particular a stent, in the blood vessel in order to keep the vessel in the dilated state. This treatment does, however, give rise to several problems with regard to the vascular healing, as the natural healing process after such an operation is not regulated and as a consequence thereof undesirable local thrombosis can take place.
After the above implantation, the intraluminal device interacts with the vessel wall surface and the bloodstream. In a clinical setting the endothelialization of the intraluminal device is generally complete within two to three months after implantation. During this period the patient is at risk of thrombotic occlusion, undesired tissue growth, inflammation and vascular dysfunction.
There are several techniques available for controlling the above undesired effects of intraluminal devices, such as for example vascular stents. Thrombosis can passively be prevented by creating an inert surface which improves the surface characteristics that influence thrombosis. Such characteristics comprise, for example, charge, wettability and topography.
Thrombosis can also be prevented by binding one or more active components which inhibit thrombosis to the stent surface in order to actively prevent thrombosis. Examples of such components are prostaglandins, heparins, other thrombin inhibitors, or enzymes such as adenosine phosphatase.
Furthermore, thrombosis can be controlled by mimicking at the stent surface an already completed thrombotic response. This can be achieved by coating the stent surface with fibrin, thereby creating a controlled thrombus in vitro, as polymerized and stabilised fibrin is no longer thrombogenetic.
Thrombus formation can also be limited by disguising the stent surface with plasma proteins such as albumin, gamma globulins or phospholipids, which causes the skipping of certain phases in the proteinaceous—thrombotic and cellular—response.
The above mentioned coatings have an anti-proliferative effect; the growth velocity is inhibited in order to prevent thrombosis or restenosis.
A coating consisting of an extract of an extracellular biologically active basement membrane composition, derived for instance from the Engelbreth-Holm-Swarm tumor has been described in U.S. Pat. No. 4,829,000. However, it appears that this membrane is not suitable as a stent coating because it forms a thick shell on the stent surface. A. Schneider et al, J. Vase. Surgery 15, 649 (1992) describe the application of a coating consisting of fibronectin whereupon bovine corneal endothelial cells grow. The cells were said to produce an extracellular matrix, and removed after 14 days. Thus coated polymer material was seeded with bovine aortic endothelial cells.
However, also this coating has a proliferative effect, viz. a large growth velocity of the cells but a big chance on thrombosis too. Moreover, this procedure is complicated and may suffer from bio-contamination.